I could wish Boeing were as stupid as the Super Efficient Airplane in your news analysis (Flight International, 7-13 January) - but it isn't. This has to be a second smokescreen behind that always-economically-absurd deception, the Sonic Cruiser.
The Super Efficient Airplane is supposed to consume "17-20% less [fuel] per passenger than a 767-300" - which is already a clean implementation of the conventional configuration pictured, with efficient engines and structure, and pretty well the same wingspan and capacity. Yet higher bypass ratios help only marginally. There isn't a great deal more to be gained from weight reduction or better wingtip sails, so induced drag will remain much the same. At best true airspeed, this is always roughly equal to the parasitic drag, the co-efficients of which must in consequence decrease by a third. How?
That wing has to be active, with flap trimming aligning the front of a highly laminarised aerofoil (with a deep but narrow drag bucket) with the airflow. It could be raised on the fuselage, eliminating those draggy root fairings. Electronic stability reduces the size of the empennage, and goes well with a minimal V-tail, which in turn would allow a drooped rear fuselage.
With all this, the promised savings might be realised, only just, but competitively lethally nonetheless. Airbus would do well to revise its designs radically, and most urgently.
Noel Falconer Couiza, France
Source: Flight International
